The present invention relates to a semiconductor module substrate sheet that constitutes a semiconductor module with one or a plurality of semiconductor chips of monolithic IC""s, hybrid IC""s, multi-tip IC""s, diodes, transistors, thyristors, or the like mounted thereon, a method for fabricating the semiconductor module substrate sheet and a semiconductor module constructed of the substrate sheet mounted with semiconductor chips mounted thereon.
Conventionally, a semiconductor package of a monolithic IC, a hybrid IC, a multi-tip IC, a diode, a transistor, a thyristor, or the like has been formed by punching by using a press, or by etching a metal conductor of a die pad and leads on which a semiconductor chip is mounted as represented by a lead frame, mounting the semiconductor chip on the die pad, and electrically connecting the electrode terminals of the semiconductor chip with inner lead sections of the leads by way of thin metal wires by bonding or similar means. Thereafter, the semiconductor chip and at least the inner lead sections on the through hole side are encapsulated and the outer lead sections of the leads are bonded by means of a die for the mounting of the semiconductor package on a printed wiring board.
However, the lead frame, which is required to support the semiconductor chip by the die pad and to be bent for the mounting thereof on the printed wiring board, has therefore, been required to have a rigidity. For the above reasons, the metallic lead frame has not been able to have a reduced thickness, and consequently, pure copper, which has good electrical conductivity, has been hard to use. Furthermore, the adjacent outer lead sections have connected portions partially connected with each other when the semiconductor chip or the like is encapsulated. Therefore, after the encapsulating process, a process has been required for cutting the connected portions (called the tie bar) with a die or the like, so the outer lead sections have independent pins.
In view of the above, there have been lately devised a number of various types of semiconductor packages 914 in which the lead material is not required to have rigidity, obviating the need for cutting the many tie bars during the fabricating process. One of the types is formed by bending a flexible substrate of a film 15 or the like provided with inner lead sections 5 and outer lead sections 6 (see FIG. 70), bonding this to a substrate 13 of the semiconductor package 914 so that the outer lead sections 6 are formed on the rear surface of the substrate 13 and so that the inner lead sections 5 and the outer lead sections 6 are connected together by way of respective connection sections 7 provided on side surfaces of the substrate 13. Thereafter, a semiconductor chip 10 is mounted on the substrate 13, and the semiconductor chip 10 is connected with the inner lead sections 5 by way of wires 11. Thereafter, the semiconductor chip 10 or the like is encapsulated with an encapsulating section 12, allowing the semiconductor package 914 to be surface-mountable (see FIG. 71).
However, the above method, which requires many fabricating steps including the formation of the inner lead sections and the like on a film and then the bending and bonding of the film, has disadvantageously been troublesome.
In recent years, some semiconductor packages such as IC""s except for diodes, transistors, and thyristors, have been required to more seriously cope with high-density mounting of semiconductor chips. In accordance with this, the inner lead sections to be electrically bonded by wire bonding or similar method to the electrode terminals of the semiconductor chip are required to have an increased number of pins and narrower pitches. In the case of the semiconductor package having an increased number of pins and narrower pitches as described above, even a slight error in positional alignment occurring in the film bending and bonding stages cannot be ignored, and this positional alignment error disadvantageously has caused difficulties in maintaining the dimensional accuracy.
Accordingly, the object of the present invention is to solve the aforementioned issues and to provide a semiconductor module which can be fabricated in a reduced number of fabricating steps, a semiconductor module substrate sheet to be used for the fabricating process, and a method for fabricating the sheet.
In order to achieve the aforementioned object, the present invention is constructed as follows.
According to a first aspect of the present invention, there is provided a semiconductor module substrate sheet comprising an insulating substrate having a semiconductor chip placement region on which a semiconductor chip can be placed. A plurality of inner lead sections are formed on a surface identical to that of the semiconductor chip placement region of the insulating substrate and respectively electrically connected to a plurality of electrode terminals of the semiconductor chip placed on the semiconductor chip placement region so as to form a semiconductor module. A plurality of outer lead sections are formed on a surface opposite to that of the semiconductor chip placement region of the insulating substrate, and a plurality of connecting sections respectively connect the plurality of inner lead sections to the plurality of outer lead sections on a side wall surface of the insulating substrate.
According to a second aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the first aspect, comprising a recess of a size capable of receiving the semiconductor chip in the semiconductor chip placement region.
According to a third aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the first or second aspect, wherein the insulating substrate has through holes and the plurality of connecting sections are formed on side wall surfaces of the through holes.
According to a fourth aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the third aspect, wherein the through holes of the insulating substrate are arranged on the two opposite sides of the semiconductor chip placement region having a rectangular shape.
According to a fifth aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the third aspect, wherein the through holes of the insulating substrate are arranged on four sides of the semiconductor chip placement region having a rectangular shape.
According to a sixth aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the first or second aspect, wherein the insulating substrate has a recess at its edge, and the plurality of connecting sections are formed on a side wall surface of the recess.
According to a seventh aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in the first or second aspect, wherein the plurality of connecting sections are formed on the side wall surface of the edge of the insulating substrate.
According to an eighth aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in any one of the first through seventh aspects, wherein the plurality of inner lead sections are arranged so as to respectively extend from the plurality of connecting sections toward the semiconductor chip placement region, and the plurality of outer lead sections are arranged so as to respectively extend from the plurality of connecting sections toward a region corresponding to the semiconductor chip placement region on a rear surface of the substrate sheet.
According to a ninth aspect of the present invention, there is provided a semiconductor module substrate sheet as defined in any one of the third through fifth aspects, wherein the plurality of inner lead sections are arranged so as to respectively extend from the plurality of connecting sections in a direction opposite to the semiconductor chip placement region. Meanwhile, the plurality of outer lead sections are arranged so as to respectively extend from the plurality of connecting sections in a direction opposite to a region corresponding to the semiconductor chip placement region on a rear surface of the substrate sheet.
According to a 10th aspect of the present invention, there is provided a method for fabricating the semiconductor module substrate sheet defined in any one of the first through ninth aspect. The method comprises providing metal layers on both surfaces of the insulating substrate and the side wall surface of the insulating substrate. Thereafter photoresist films are formed on the metal layers. The formed photoresist films are then partially exposed to light and then developed for patterning of etching resist layers that exist in portions to be left as the inner lead sections and the outer lead sections and portions to be left as the connecting sections on the side wall surface. Thereafter, the metal layer is removed by etching portions that are not covered with the etching resist layers. Thereafter, the etching resist layer is removed to form the inner lead sections, the outer lead sections, and the connecting sections.
According to an 11th aspect of the present invention, there is provided a method for fabricating the semiconductor module substrate sheet defined in any one of the first through ninth aspects. The method comprises forming photoresist films on both surfaces of the insulating substrate and the side wall surface of the insulating substrate. Thereafter, the photoresist films are then partially exposed to light and then developed the same for patterning of plating resist layers that exist in unnecessary portions of the inner lead sections and the outer lead sections and unnecessary portions of the connecting sections on the side wall surface. Thereafter, the inner lead sections, the outer lead sections, and the connecting sections in portions that belong to both surfaces of the insulating substrate and the side wall surface are formed by performing electroless plating or electroplating and are not covered with the plating resist layer.
According to a 12th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 10th aspect, wherein the photoresist film is a photocurable type when patterning the etching resist layer. The exposing to light is performed with a first mask in which lead pattern forming-sections for forming the inner lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions do not transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a second mask in which lead pattern forming-sections for forming the outer lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions do not transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on the other surface of the substrate, resulting in curing only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of uncured portions other than cured portions to form the etching resist layer in portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 13th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 10th aspect, wherein the photoresist film is a photolysis type when patterning the etching resist layer. The exposing to light is performed with a third mask in which lead pattern forming-sections for forming the inner lead sections and connection pattern forming-sections for forming the connecting sections obstruct light and the other portions transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a fourth mask in which lead pattern forming-sections for forming the outer lead sections and connection pattern forming-sections for forming the connecting sections obstruct light and the other portions transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on the other surface of the substrate, resulting in photolysis of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of only portions that have undergone photolysis to form the etching resist layer in portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 14th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 10th aspect, wherein the photoresist film is a photocurable type when patterning the etching resist layer. The exposing to light is performed with a fifth mask in which lead pattern forming-sections for forming either one of the inner lead sections and the outer lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions do not transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is performed with a sixth mask in which only lead pattern forming-sections for forming the other one of the inner lead sections and the outer lead sections transmit light and the other portions do not transmit light superposed on the other surface of the substrate, resulting in curing of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of uncured portions other than cured portions to form the etching resist layer in portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 15th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 10th aspect, wherein the photoresist film is a photolysis type when patterning the etching resist layer. The exposing to light is performed with a seventh mask in which lead pattern forming-sections for forming either one of the inner lead sections and the outer lead sections and connection pattern forming-sections for forming the connecting sections obstruct light and the other portions transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with an eighth mask in which lead pattern forming-sections for forming the other one of the inner lead sections and the outer lead sections and sections to be superposed on the through holes obstruct light and the other portions transmit light superposed on the other surface of the substrate, resulting in photolysis of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of portions that have undergone photolysis to form the etching resist layer in portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 16th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 11th aspect, wherein the photoresist film is a photocurable type when patterning the plating resist layer. The exposing to light is performed with a ninth mask in which lead pattern forming-sections for forming the inner lead sections and connection pattern forming-sections for forming the connecting sections do not transmit light and the other portions transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a tenth mask in which lead pattern forming-sections for forming the outer lead sections and connection pattern forming-sections for forming the connecting sections do not transmit light and the other portions transmit light. A light control sheet then diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on the other surface of the substrate, resulting in curing of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of uncured portions other than cured portions to form the plating resist layer in portions other than portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 17th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 11th aspect, wherein the photoresist film is a photolysis type when patterning the plating resist layer. The exposing to light is performed with an eleventh mask in which lead pattern forming-sections for forming the inner lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions obstruct light. A light control sheet that diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a twelfth mask in which lead pattern forming-sections for forming the outer lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions obstruct light. Another light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on the other surface of the substrate, resulting in photolysis of only exposed portions of the photoresist film Thereafter, the photoresist film is developed for the removal of only portions that have undergone photolysis to form the plating resist layer in portions other than portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to an 18th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 11th aspect, wherein the photoresist film is a photocurable type when patterning the plating resist layer. The exposing to light is performed with a thirteenth mask in which lead pattern forming-sections for forming either one of the inner lead sections and the outer lead sections and connection pattern forming-sections for forming the connecting sections do not transmit light and the other portions transmit light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a fourteenth mask in which lead pattern forming-sections for forming the other one of the inner lead sections and the outer lead sections and portions to be superposed on the through holes do not transmit light and the other portions transmit light superposed on the other surface of the substrate, resulting in curing of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of uncured portions other than cured portions to form the plating resist layer in portions other than portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 19th aspect of the present invention, there is provided a semiconductor module substrate sheet fabricating method as defined in the 11th aspect, wherein the photoresist film is a photolysis type when patterning the plating resist layer. The exposing to light is performed with a fifteenth mask in which lead pattern forming-sections for forming either one of the inner lead sections and the outer lead sections and connection pattern forming-sections for forming the connecting sections transmit light and the other portions obstruct light. A light control sheet diffuses or refracts incident light and then emits the light from a side opposite from an incident side superposed on one surface of the substrate. The exposing to light is then performed with a sixteenth mask in which only lead pattern forming-sections for forming the other one of the inner lead sections and the outer lead sections transmit light and the other portions obstruct light superposed on the other surface of the substrate, resulting in photolysis of only exposed portions of the photoresist film. Thereafter, the photoresist film is developed for the removal of only portions that have undergone photolysis to form the plating resist layer in portions other than portions where the inner lead sections, the outer lead sections, and the connecting sections are formed.
According to a 20th aspect of the present invention, there is provided a semiconductor package substrate sheet fabricated by the semiconductor module substrate sheet fabricating method defined in any one of the 10th through 19th aspects.
According to a 21st aspect of the present invention, there is provided a substrate sheet as defined in any one of the first through ninth and 20th aspects, provided with a metal conductor section having a size equal to or larger than a size of the semiconductor chip placed in the semiconductor chip placement region.
According to a 22nd aspect of the present invention, there is provided a substrate sheet as defined in any one of the first through ninth and 20th aspects, wherein a first metal conductor section having a size equal to or larger than a size of the semiconductor chip is placed in the semiconductor chip placement region, and a second metal conductor section is provided in a region on a rear surface side of the insulating substrate oppositely from the first metal conductor section located on a front surface side of the insulating substrate across the insulating substrate. The first metal conductor section and the second metal conductor section are connected with each other by way of through holes.
According to a 23rd aspect of the present invention, there is provided a substrate sheet as defined in the 22nd aspect, wherein hole portions of the through holes that connect the first metal conductor section with the second metal conductor section are filled up with resin.
According to a 24th aspect of the present invention, there is provided a substrate sheet as defined in the 23rd aspect, wherein metal layers are further placed on the first metal conductor section and the second metal conductor section, respectively. The first and second metal condition sections are connected with each other by way of the through holes with the hole portions of the through holes filled up with the resin. The metal layer covering the first metal conductor section, the second metal conductor section, and hole portions of the through holes filled up with the resin.
According to a 25th aspect of the present invention, there is provided a substrate sheet as defined in any one of the 21st through 24th aspects, wherein the metal conductor section has the inner lead sections or the outer lead sections partially extended to the semiconductor chip placement region so as to be formed with a size capable of mounting the semiconductor chip.
According to a 26th aspect of the present invention, there is provided a semiconductor substrate sheet in which an insulating substrate is provided with through holes, connecting sections are provided on side wall surface oppositely from a semiconductor chip placement region, inner lead sections are extended in a direction away from the connecting sections, and outer lead sections are extended from the connecting sections in a direction away from a region corresponding to a rear surface of the semiconductor-chip placement region. A a metal conductor section is formed in the semiconductor chip placement region.
According to a 27th aspect of the present invention, there is provided a semiconductor substrate sheet in which an insulating substrate is provided with through holes, connecting sections are provided on a side wall surface oppositely from a semiconductor chip placement region, inner lead sections are extended in a direction away from the connecting sections, and outer lead sections are extended from the connecting sections in a direction away from a region corresponding to a rear surface of the semiconductor chip placement region. Further, other connecting sections are provided so as to not come in contact with the connecting sections on the side wall surface located on the semiconductor chip placement region side of the through holes. A metal conductor section is provided for the semiconductor chip placement region, a metal layer section is provided for a region corresponding to the rear surface of the semiconductor chip placement region, and the metal conductor section and the metal layer section are connected together by way of said other connecting sections.
According to a 28th aspect of the present invention, there is provided a substrate sheet as defined in the 26th or 27th aspect, wherein the through holes are filled up with resin.
According to a 29th aspect of the present invention, there is provided a substrate sheet as defined in any one of the 21st through 28th aspects, wherein the metal conductor section placed on a surface of the substrate sheet on which the inner lead sections are formed has a flat front surface.
According to a 30th aspect of the present invention, there is provided a substrate sheet as defined in any one of the 21st through 28th aspects, wherein the metal conductor section placed on a surface of the substrate sheet on which the inner lead sections are formed has minute undulations or patterned recesses on its front surface.
According to a 31st aspect of the present invention, there is provided a semiconductor module in which the semiconductor chip is placed in the semiconductor chip placement region of the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects, and the plurality of electrode terminals of the semiconductor chip are electrically connected with the plurality of inner lead sections, respectively.
According to a 32nd aspect of the present invention, there is provided a semiconductor module in which the semiconductor chip is placed in the semiconductor chip placement region of the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects, and the plurality of electrode terminals of the semiconductor chip are electrically connected with the plurality of inner lead sections by way of wires, respectively.
According to a 33rd aspect of the present invention, there is provided a semiconductor module in which the semiconductor chip is placed in the semiconductor chip placement region of the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects, and bumps formed on the plurality of electrode terminals located on a rear surface of the semiconductor chip are electrically connected with the plurality of inner lead sections, respectively.
According to a 34th aspect of the present invention, there is provided a semiconductor module in which the semiconductor chip is placed in the semiconductor chip placement region of the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects, and the plurality of electrode terminals located on a rear surface of the semiconductor chip are electrically connected with the plurality of inner lead sections by way of anisotropic conductive adhesive, respectively.
According to a 35th aspect of the present invention, there is provided a semiconductor module in which the semiconductor chip is received and held in a recess located in the semiconductor chip placement region of the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects.
According to a 36th aspect of the present invention, there is provided a semiconductor module obtained by providing the substrate sheet defined in any one of the first through ninth and 20th through 29th aspects with a plurality of rectangular semiconductor chip placement regions. A semiconductor chip is placed in each of the plurality of semiconductor chip placement regions. The plurality of electrode terminals of the semiconductor chip are electrically connected with the plurality of inner lead sections. Thereafter, the substrate sheet is cut in correspondence with each of the semiconductor chip placement regions.